Service Manual Instruction Manual

SECTION 4 - BOOM & PLATFORM
4-2 – JLG Lift – 3121171
4.5 JIB STOW SYSTEM
This machine is equipped with a full function side swing rota-
tor that is mechanically limited to 55 degree rotation to the
left and electrically limited to 70 degrees to the right through
the use of a positive action limit switch mounted on the rota-
tor assembly. The machines stowed length can be reduced to
facilitate transportation on standard trailers by swinging the
jib further to the right using the hydraulic power of the side
swing rotator. The control system will prevent swinging the jib
past the 70 degree position unless the axles are retracted, the
boom is in the transport position (see Section 4.2, Transport
Position Sensing System), and the jib stow override button on
the platform control panel is held in combination with the jib
swing function switch. When the jib is stowed, automatic plat-
form leveling is disabled, the boom is restricted to the trans-
port position, and axle extension is disabled. This system is
functional only in the 500# (230 kg) mode of the Dual Capacity
System (see Section 4.13, Dual Capacity System).
NOTE: For more detailed information concerning system adjust-
ment and operation, refer to Section 6 - JLG Control Sys-
tem.
4.6 ENVELOPE CONTROL SYSTEM
The Envelope Control System is the primary means of control-
ling the working positions of the tower and main boom within
the stability and structural requirements of the machine.
Although the machine includes a load pin capable of measur-
ing the changing forces on the boom, it is used exclusively for
boom retrieval as described in the electrical retrieval system
(see Section 4.9, Electrical Retrieval System) and is not used for
controlling the stability of the machine until a fault is detected
within the primary envelope control system. The control sys-
tem is therefore not considering the load on the machine but
rather the measured position of the boom within the enve-
lope.
The main boom must be controlled in maximum angle and
minimum angle to avoid entering a position that could com-
promise backward stability and avoid main boom to tower
boom interference. The tower boom must be controlled by
permitting only specific combinations of tower length and
tower angle to avoid entering a position that could compro-
mise forward and backward stability (see Section 4.7, Tower
Path Control System).
This system uses two gravitationally based angle sensors and
two length sensors to continuously measure the position of
the tower boom in addition to two rotary angle sensors to
continuously measure the position of the main boom. Each
pair of sensors are continuously monitored for mutual agree-
ment, proper response to command, and for correlation to a
main boom angle limit switch, a tower boom length limit
switch, and a tower rotary angle sensor. Recognized faults
within this system will result in control by the Electrical
Retrieval System (Section 4.9, Electrical Retrieval System),
reduced function speeds, and BCS warning light illumination.
After retrieval the boom will be restricted from leaving the
transport position (see Section 4.2, Transport Position Sensing
System) until the fault is resolved.
Boom position violations outside of the allowable envelope
will result in reduced function speeds, BCS warning light illu-
mination, restriction of functions, and sounding of the plat-
form alarm and the flashing of the BCS light with attempts to
operate restricted functions.
Normally, the tower lift function switch on the ground and
platform control panels automatically activates both tower lift
and tower telescope as described in the tower path control
system (see Section 4.7, Tower Path Control System). Violations
of the tower envelope will result in the suspension of this
automatic feature. In an otherwise healthy control system, vio-
lations of the tower envelope can be corrected by actuating
either of the tower lift up or tower lift down directions of the
tower lift switch regardless of the direction of the violation.
The control system will telescope or lift the tower in a singular
manner to correct the tower position.
The restricted functions due to backward tower envelope vio-
lations are disallowing automatic tower lift down with tower
lift down commands, automatic tower telescope out with
tower lift up commands, main lift up and down, main tele-
scope in, jib, swing, drive and steer.
The restricted functions due to forward tower envelope viola-
tions are disallowing automatic tower lift up with tower lift up
commands, automatic tower telescope in with tower lift down
commands, main lift up and down, main telescope out, jib,
swing, drive and steer.
The restricted functions due to maximum main boom enve-
lope violations are disallowing tower lift up and down, main
lift up, main telescope in, jib, swing and drive.
The restricted functions due to minimum main boom enve-
lope violations are disallowing main lift down, swing and
drive.
NOTE: For more detailed information concerning system adjust-
ment and operation, refer to Section 6 - JLG Control Sys-
tem.